Various medical procedures require the transfer of fluid from one fluid-containment system or fluid-conducting system to another fluid-containment system or fluid-conducting system. Typically, one of the two systems is connected directly to a patient in some manner for a substantial period of time. The other system may be connected to the first system for only a short period of time, or intermittently, to collect an effluent flow of a fluid or fluids from the patient or to supply a fluid or fluids to the patient.
The fluid flow system that is directly connected to the patient may be regarded, for purposes of discussion, as the first system and may include a connection device which can function as a so-called "injection site" for being penetrated by a transferring device such as a hollow needle or cannula of a syringe. A fluid may be dispensed from, or collected by, the syringe needle or cannula through the injection site. The syringe, along with its hollow needle or cannula, and other fluid containers and transferring devices may be regarded in this context as the second fluid flow system.
In other procedures, the first fluid flow system that is connected directly to the patient may be engaged with an appropriate cannula or other conduit that is part of a second fluid flow system which also includes flexible tubing connected to either a receiving container (e.g., collection bag) or a supply reservoir (e.g., container of a liquid agent to be introduced into the patient).
It is usually desirable, where possible, to avoid the use of a needle or sharp cannula. A person using, or exposed to, a needle may accidentally puncture his or her skin, or may accidentally puncture the skin of another person. Because such a needle may have been used in patient treatment procedures and/or otherwise brought into contact with patient fluids or other contaminants, there is a risk of becoming infected as a result of such an accidental puncture. Likewise an accidental puncture may result in an adverse reaction to a drug used in IV therapy. Accordingly, there is great interest in developing and using systems which can eliminate, where possible, the use of a hollow needle or sharp cannula to establish fluid flow connections.
Connection devices for use with a blunt cannula, which do not puncture the skin, have been disclosed in U.S. Pat. No. 4,197,848 and in published Patent Cooperation Treaty international patent application No. PCT/US89/00273 (International Publication No. WO 89/06553). U.S. Pat. No. 4,197,848 discloses an irrigation site which has a resilient membrane with a slit for accommodating penetration by a blunt end syringe. The resilient membrane extends generally transversely across a passage in a housing in which the membrane is mounted, and the periphery of the membrane includes a generally cylindrical skirt for being retained in an annular channel of the housing.
International patent application No. PCT/US89/00273 discloses a variety of embodiments of a system which includes an injection site for a blunt cannula. The site employs a housing having a distal end defining an opening for accommodating insertion of the blunt cannula. In most of the disclosed embodiments, an annular, tapered, interior surface is defined by the housing inwardly of the opening, and the diameter of the tapered surface decreases with increasing distance away from the opening at the distal end of the housing. A resilient septum having a slit is provided to engage the tapered interior surface of the housing. The end of the housing is swaged against the periphery of the septum to apply axial forces to the septum while the internal, tapered surface of the housing applies radially directed forces to the septum for forcing the septum slit into a resealed condition. FIG. 27 of the application discloses an alternate, non-tapered embodiment which is described as providing "compression to create a seal against pressure and a void region to accommodate deformed portions of the sealing member material only when the material is deformed or displaced by a blunt cannula piercing member."
Although the above-discussed connection device and injection site designs may function satisfactorily in certain applications--within certain pressure ranges and with certain sizes and configurations of cannula--it would be desirable to provide an improved connection device offering advantages and features that have been heretofore unavailable.
In particular, it would be desirable to provide an improved connection device which could be manufactured without requiring the imposition of extremely strict and critical manufacturing tolerances. It would be beneficial if such an improved device could be manufactured within a range of tolerances without deleteriously affecting its performance or without degrading the sealing and resealing integrity or capability of the device.
Further, in view of the danger of contamination and infection, it would be desirable to provide a connection device which would facilitate its use as a disposable item. To this end, the improved device should be relatively inexpensive. Accordingly, the device should incorporate an improved component design that accommodates relatively simple manufacturing processes and assembly processes so as to keep the total cost as low as possible.
An improved connection device should also function to effectively seal around a blunt cannula, as well as reseal after the cannula is removed, so as to prevent unwanted leakage of fluids and so as to prevent ingress of airborne or liquid-carried contaminants.
The improved device should also preferably accommodate use with a variety of fluids throughout a range of fluid pressures.
Advantageously, the improved device should have a suitably long shelf life and active use life. Further, it should function effectively after repeated penetrations and removals of a blunt cannula.
Finally, it would be desirable for such an improved connection device to facilitate handling and use by medical personnel. In particular, the device should accommodate initial insertion of a blunt cannula, should provide engaging forces and/or latches sufficient to prevent inadvertent withdrawal of the cannula, and should nevertheless permit the cannula to be withdrawn by appropriate manipulation.
The present invention provides an improved connection device which can accommodate designs having the above-discussed benefits and features.